Caffeine May Lower Risk of Common Skin Cancer

Action Points

Note that this study used data from the Nurses' Health Study and the Health Professionals Follow-up Study to examine the risks of basal cell carcinoma, squamous cell carcinoma, and melanoma in relation to caffeine intake.

Point out that the investigators found that caffeine from coffee and other dietary sources was inversely associated with risk of basal cell carcinoma.

People who consumed more than three cups of coffee a month had a 17% reduction in the relative risk of BCC versus individuals who drank less than one cup per month.

The association pertained to men and women and to sources of caffeine other than coffee.

Investigators found no association between caffeine consumption and squamous-cell carcinoma (SCC) or melanoma, as reported in the July 1 issue of Cancer Research.

"Given that nearly one million new cases [of BCC] are diagnosed each year in the U.S., modification in daily dietary factors with even small protective effects may have great public health impact," Jilali Han, PhD, of Harvard and Brigham and Women's Hospital in Boston, and co-authors wrote in conclusion.

Skin cancers are the most common malignancy among white people in the U.S. White Americans have an estimated 1 in 5 lifetime risk of developing skin cancer.

Laboratory studies have consistently shown that oral and topical caffeine prevents SCC in mice exposed to ultraviolet (UV) light, the authors wrote in their introduction. Other preclinical studies have suggested a potential mechanistic explanation, as topical caffeine has been shown to induce apoptosis in UV-damaged keratinocytes in mice.

Observational data have been less convincing, as studies have shown inconsistent associations between caffeine and skin cancer, including melanoma and nonmelanoma. None of these studies distinguished between caffeinated and decaffeinated coffee or tea, a key piece of evidence that might show whether other components of coffee or tea have anticancer activity.

To address limitations of current information, Han and co-authors reviewed data from the Nurses' Health Study (NHS) and the Health Professionals Follow-up Study (HPFS). The NHS included 121,700 women ages 30 to 55 at enrollment in 1976. HPFS enrolled 51,529 men ages 40 to 75 when the study began in 1976.

NHS participants provided information on caffeine intake on several occasions from 1984 to 2006, as did the HPFS participants from 1986 to 2006.

Han and co-authors analyzed data for 112,897 participants from the two studies (72,921 women and 39,976 men). During 24 and 22 years of follow-up in the NHS and HPFS, respectively, 22,786 participants developed BCC, 1,953 developed SCC, and 741 developed melanoma.

Using U.S. Department of Agriculture data, Han and co-authors estimated caffeine content 137 mg per cup of caffeinated coffee, 47 mg per cup of tea, 46 mg per 12-oz container of caffeinated soda, and 7 mg per 1-oz serving of chocolate.

Investigators stratified the study participants into quintiles of daily caffeine consumption, which range from 31 to 604 mg in NHS and 8 to 584 mg in the HPFS. The analysis showed an inverse association between caffeine consumption from all sources combined and the risk of BCC.

Comparison of the highest and lowest quintile of caffeine consumption resulted in a relative risk of 0.82 for BCC in women and 0.87 in men (P<0.0001 for trend in both groups). The relative risk was 0.84 for men and women combined.

Coffee accounted for 78.5% of all caffeine consumption. A separate comparison of skin cancer risk by coffee consumption produced a relative risk of 0.83 for the highest versus lowest quintile (95% CI 0.77 to 0.87). Investigators found a dose-response relationship between caffeine and BCC risk in women (P<0.0001 for trend) and men (P=0.003 for trend).

Caffeine from sources other than coffee tended to have an inverse association with BCC (0.88 in women, 0.93 in men), although the effect did not achieve statistical significance.

The authors noted a number of limitations including the reliance on self-report of BCC without confirmation from histology. Also, they noted that statistical power to calculate any relationship between caffeine and melanoma or SCC was lacking because the number of those cancers in the population was much lower than BCC.

Finally, they said they were "not able to rule out other differences between caffeinated and decaffeinated coffee that could also be etiologically relevant."

The study was supported by internal institutional resources.

The authors had no disclosures.

Reviewed by Zalman S. Agus, MD Emeritus Professor, Perelman School of Medicine at the University of Pennsylvania and Dorothy Caputo, MA, BSN, RN, Nurse Planner

MedPageToday is a trusted and reliable source for clinical and policy coverage that directly affects the lives and practices of health care professionals.

Physicians and other healthcare professionals may also receive Continuing Medical Education (CME) and Continuing Education (CE) credits at no cost for participating in MedPage Today-hosted educational activities.